Is CO2 the cause for Global Warming?

Question

I know there is global warming, and I know that it is caused by human activity, but is carbon dioxide the cause of it? I read somewhere that apparently increase of CO2 doesn't cause the increase in global temperatures, but rather, global temperatures cause the increase of CO2. Can someone verify or disprove this claim?

Answer 1

The Earth’s greenhouse effect is a natural occurrence that helps regulate the temperature of our planet. When the Sun heats the Earth, some of this heat escapes back to space. The rest of the heat, also known as infrared radiation, is trapped in the atmosphere by clouds and greenhouse gases, such as water vapor and carbon dioxide. If all of these greenhouse gases were to suddenly disappear, our planet would be 60ºF (33ºC) colder and would not support life as we know it. Human activities have enhanced the natural greenhouse effect by adding greenhouse gases to the atmosphere, very likely (greater than 90 percent chance) causing the Earth’s average temperature to rise. These additional greenhouse gases come from burning fossil fuels such as coal, natural gas, and oil to power our cars, factories, power plants, homes, offices, and schools. Cutting down trees, generating waste and farming also produce greenhouse gases.

Source: The Environmental Protection Agency (EPA)

http://www.epa.gov/climatechange/fq/science.html

You may also want to read:

http://www.epa.gov/climatechange/science/stateofknowledge.html

This page acknowledges the gaps in scientific climate knowledge, and differentiates fact from speculation/uncertain predictions.

Answer 2

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Carbon Dioxide:

Carbon dioxide is one of the greenhouse gases.

When its atoms are bonded tightly together, the carbon dioxide molecule can absorb infrared radiation and the molecule starts to vibrate.
Eventually, the vibrating molecule will emit the radiation again, and it will likely be absorbed by yet another greenhouse gas molecule.

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This absorption-emission-absorption cycle serves to keep the heat near the surface, effectively insulating the surface from the cold of space.

Here are some research papers on the absorption properties of CO2.

From John Cook:

In 1970, NASA launched the IRIS satellite that measured infrared spectra between 400 cm^-1 to 1600 cm^-1.
In 1996, the Japanese Space Agency launched the IMG satellite which recorded similar observations.

[Harries 2001] compared both sets of data to discern any changes in outgoing radiation over the 26 year period.

What they found was a drop in outgoing radiation at the wavelength bands that greenhouse gases such as CO2 and methane (CH4) absorb energy.

The change in outgoing radiation was consistent with theoretical expectations.
Thus the paper found "direct experimental evidence for a significant increase in the Earth's greenhouse effect".

This result has been confirmed by subsequent papers using data from later satellites (Griggs 2004, Chen 2007).

Simply put:
Satellites measuring infrared (heat) radiation coming from our Earth found that CO2 (and other greenhouse gases) won't let it escape into space.

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Answer 3

How much CO2 is in the atmosphere is critically important, as are the other greenhouse gases (methane, some oxides of nitrogen, water and others). This is becuase these gases trap the (heat) energy from the sun in our atmosphere, while the majority of the gas (oxygen and nitrogen) does not. While the greenhouse gases have maintained a relatively stable temperature on Earth, over millions of years, the EXTRA greenhouse gases that humans have pumpted into the atmoshpere have added extra heat to be accumulated/trapped. Have humans caused the extra amount of the greenhouse gases in recent human history - yes. Please see David Attenborough for a very quick and easily digestable video at:http://www.youtube.com/watch?v=S9ob9WdbXx0 There is no doubt about the science, only about the quality of the politics involved and people's fears.

Answer 4

There definitely is global warming but many people doubt the influence of mankind to this fact. Without referencing any datasets which would be too much to evaluate for a non scientific use, there is a very important issue which everyone may think about on their own.

CO2 is a so called [trace gas][1] with a rate of ~390ppm - thats parts per million. So every million partikels of air contain only!! around 390parts of carbon dioxide. The base theorie of the common man made(CO2 based) global warming refers to a theorie the radiation is reflected when "hitting" a CO2 partikel in the atmosphere. I guess the rate of 390ppm clearly shows that CO2 can't be responsible for such an effect.

Anyway assuming the carbon dioxide builds up some kind of shell around the globe which preserves the heat by reflecting in a significant way. In that case this effect would have to occur in both directions (SUN <-> CO2-shell <-> surface). With an implication of the temperature to stay stable or even falling but surely not raising.

Another interesting thing is that the [IPCC - Intergovernmental Panel on Climate Change][3] charges mankind for around 5% of the CO2 in the atmosphere( thats 5% of 390ppm summing up to around 20ppm). So assuming the IPCC is right mankind is only responsible for around 20ppm of CO2 and therefore hardly can be responsible for the climate change.

I know this explanation isn't very scientific but it's just too much information to be properly revealed in such a short text. For more interested people hier is a lecture by Lord Monckton concerning this issue.